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DHS has maintained that courthouses are not considered "sensitive locations"

The letter was a response to California Chief Justice Tani Cantil-Sakauye's complaint

Washington (CNN)The Departments of Justice and Homeland Security said this week that immigration agents will continue to make arrests at courthouses -- and encouraged cities to revoke their sanctuary policies if they object.

The letter, released Friday but sent Wednesday, was a response to California Chief Justice Tani Cantil-Sakauye, who wrote to Attorney General Jeff Sessions and DHS Secretary John Kelly saying that Immigrations and Customs Enforcement "appear to be stalking undocumented immigrants in our courthouses to make arrests."

The subject of ICE arrests at courthouses has been particularly sensitive in recent weeks between major cities and federal officials, as local jurisdictions have complained that arresting undocumented immigrants in courthouses has a chilling effect on their participation in prosecuting criminals as witnesses and reporting victims.

Los Angeles has said reporting of crimes like sexual assault and domestic violence are down by one-quarter in immigrant communities.

"Our courthouses serve as a vital forum for ensuring access to justice and protecting public safety," Cantil-Sakauye wrote in her letter earlier this month. "Courthouses should not be used as bait in the necessary enforcement of our country's immigration laws."

But DHS has maintained that courthouses are not considered "sensitive locations" and that apprehending individuals in controlled environments is safer than doing so on the street.

In their letter, Sessions and Kelly object to Cantil-Sakauye's use of the word "stalking," saying ICE is constitutionally and lawfully authorized to arrest anyone with probable cause.

They also insist that arrests by ICE are targeted and not indiscriminate -- though advocacy groups have complained that ICE has arrested non-criminal undocumented immigrants in recent stepped-up enforcement.

As the administration continues to pressure sanctuary cities, the attorney general and DHS secretary criticized California and its jurisdictions for having policies of non-cooperation with ICE -- blaming those policies for the courthouse arrests.

"Some jurisdictions, including the State of California and many of its largest counties and cities, have enacted statutes and ordinances designed to specifically prohibit or hinder ICE from enforcing immigration law by prohibiting communication with ICE, and denying requests by ICE officers and agents to enter prisons and jails to make arrests," Sessions and Kelly wrote. "As a result, ICE officers and agents are required to locate and arrest these aliens in public places, rather than in secure jail facilities where the risk of injury to the public, the alien, and the officer is significantly increased because the alien can more readily access a weapon, resist arrest, or flee."

Sessions and Kelly said that because courthouses require screening for entry, they are the safest places to make arrests of known targets.